Grid making machine



1946.. I D. F. DRIESCHMAN ETAL' 88 GRID MAKING MACHINE Filed March 11, 1944 8 Sheets-Sheet l INVENTORS Donald F. Dneschman- Gordon Shepherd- Mendel Rab/hm /yz A/mer M. NQW/ldl/L/r.

Harold E. org. M E jg ATTCSRNEY 3, 1946- D. F. DRIESCHMAN ETAL I 2,411,988

GRID MAKING MACHINE Filed March 11, 1944 8 Sheets-Sheet 2 INVENTORS Donald E. Dr/eschman -fiardan Shep/verd- Mende/ kablhgyifz 14/me/' M. New/MIN.

Harold E. org. M 5 i1,

Dec. 3, 1946. D. F. DRIESCHMAN ET AL- 2,411,988

GRID MAKING MACHINE Filed March 11, 1944- 8 Sheets-Sheet 5 INVENTORS Dana/d E Driesc/rman-Gardon Shepherd- Mendel Fab/rmu/ifz-A/mer M. NWbfl//t/z BY fiaro/d E. org.

ATTORNEY 1946- D. F. DRIESCHMAN ETAL 2,411,988

GRID MAKING MACHINE 8 Sheets-Sheet 4 Filed March 11. 1944 ILL-.5

8 Sheets-Sheet 5 Dec. 3, 1946. D. F. DRIESCHMAN ETALq GRID MAKING MACHINE Filed March ll, 1944 Dec. 3,- 1946. D. F. DRIESCHMAN ET AL 2,411,983

GRID MAKING MACHINE 8 Sheets-Sheet 6 Filed March 11, 1944 INVENTORS Dona/dliDr/esch Mandel Rab/nan if ATTO RNEY Dec. 3, 1946.

D. F. DRIESCHMAN EI'AL GRID MAKING MACHINE s Sheets-Sheet 8 Filed March 11, 1944 a Y m E e e .N h mswu R Ma 0 W; T -Mm m. i n p 8 M mm 0 Patented Dec. 3, 1946 GRID MAKING lVIACHINE Donald F. Driesclunan, San Carlos, Gordon Shepherd, Burlingame, Mendel Rabinawitz, San

Francisco, Almer M. Newhall, and Harold E. Sorg,

17 Claims.

Our invention relates to apparatus for making grid electrodes for electron tubes. This application covers the machine, the method being claimed in our copending application, Serial No. 526,093, and the product being claimed in our copending application Serial No. 526,091.

- tion of our invention. It is to be understood that We do not limit ourselves to this disclosure of .species of our invention as we may adopt variant embodiments thereof within the scope of the claims.

Referring to the drawings:

Figure 1 is a side elevaticnal view showing a completed grid and also a series of grids as made on a mandrel by our machine.

Figure 2 is a side elevational view of our machine; and

Figure 3 is a plan View of the same.

Figure 4 is a rear end elevational view showing the supply rolls for laying the longitudinal grid bars on the mandrel.

Figure 5 is a transverse vertical sectional view taken in a plane indicated by line 5-5 of Figure 3, showing the winding head.

Figure dis a longitudinal vertical sectional View taken in a plane axially of the mandrel through the winding head.

Figure '7 is a detail sectional view showing the welding roller mounting, taken in a plane indicatedby line 'l'l of Figure 5; and

Figure 8 is another sectional view of this structure, taken in a plane indicated by line 8-8 of Figure 5.

Figure 9 is a fragmentary sectional view showing the slide .contactor for the winding head, taken in a plane indicated by line 9-9 of Figure 2.

Figure 10 is a detail sectional view of the cam mechanism which controls axial movement of the winding head, taken in a plane indicated by line |il-i 0 of Figure 2.

Figure 11 is a detail sectional view of the winding head drive gearing, taken in a plane indicated byline I I--l I of Figure 5.

In terms of broad inclusion, our grid making apparatus comprises means for laying a plurality of wires longitudinally of an axis to form bars for a connected series of grids, means for winding Jr., Palo Alto,

Redwood City, Calif., assignors to Eitel-McCullough, Inc., San Bruno, Calif., a corporation of California Application March 11, 1944, Serial No. 526,092

another wire helically about the bars, and means for uniting the wires at their intersections. By this arrangement the grids may be formed continuously on a mandrel. Means-are also provided for varying the pitch of the winding at intervals along the axis, and means are further provided for controlling the pitch varying means to provide close-turn end rings on the grids and open turn helices between the end rings. Means are still further supplied for severing the Wires between adjacent end rings to separate the grids. Special features are also incorporated in numerous detail parts of the apparatus, such as the winding mechanism, welding device and timing system.

In greater detail, and referring to Figure 1 of the drawings, our apparatus is designed to automatically fabricate a grid comprising a plurality of longitudinal wire bars 2 spaced about the grid axis. These bars are parallel and lie in cylindrical formation about the axis. The longitudinal grid bars are held by another wire wound about and welded to the bars, this winding being applied to form close-turn end rings 3 and 4 on each grid and an open-turn helix 6 between the end rings. Base ring 3 to which the grid supports are usually connected is preferably wider than the top ring, governed by the number of close turns provided, as shown on the completed grid at the right in Figure 1.

This grid structure is adapted for being made continuously on a mandrel I by simply laying the longitudinal wires 2 to form a connected series of grids and then forming the end rings 3 and 4 and helices 6 by a continuous winding operation. After the winding has been applied and welded .the wires are severed in transverse planes be- .tween adjacent end rings to separate the grids. This severing may be done by any suitable means as by a knife 8. As the mandrel may be injured by this cutting operation we prefer to strip the connected grids from the winding mandrel and :slip them on a core of harder material.

Frame structure and mandrel guides.-Referring to Figures 2 and 3, our machine comprises a fixed frame including a bed plate 9 supported on side channels I l and carrying a transverse upright plate 12 between braces [3, upon which the various components of the apparatus are mounted. A central aperture is provided in plate [2 through which mandrel l advances (Fig. 6). For convenience in making the grids a plurality of mandrels are employed, each about three feet long. These are held in axial alignment on opposite sides of plate 12 by V-shaped guides l4 and [5. One mandrel section follows immediately behind the other so that in effect a continuous mandrel is provided. A flat tip IS on one end of each mandrel section engages a slot in the end of another section to restrain the mandrels .against relative rotation.

M andrel feed mechanism.-Means are provided for feeding the mandrels axially through the machine. For this purpose two sets of drive rollers l1 and [3 are arranged to engage opposite sides of the mandrels, the rear set Ii being driven at a slightly faster rate to insure tight abutment of the mandrel sections. Rollers H are frictionally held on their shafts by springs I9 to allow for a degree of slippage. Figures 2 and 3 show 7 these drive rollers mounted on shafts 2i journaled in a gear box 22. A cross shaft 23 is geared to the roll shafts by worm drives 24, the cross shaft being connected through a gear train 26 to the main drive shaft 21 extending along the bed of the machine and journaled in bearings 28.

I By this driving arrangement the mandrels are axially moved at a constant'speed through the wire winding mechanism.

Longitudinal wire laying mechanism.-Means As best shown in Figures 4 and 6,

Wires 2 tionally'held by spiders 33 pressed by springs 34.

1 Wires 2 pass through a sleeve 36 slidably mounted in a hollow hub 31 which projects from the front side ofjplate l2. A guide tip 38 on sleeve 3'5 slida- T bly engages the mandrel to support the latter and ."has a- 'series of radial guide slots 38 through which the wires pass. wardly adjacent the rear end of sleeve. 36 serve Centering lugs 4| projecting inas another support for the mandrel. See Figures f 5, 6 and 8.

" Wire winding mechanisr".-'-Means are provided for applying the helical winding on the grids. For this purposea winding head generally indicated by numeral 42 is mounted for rotation about the mandrel. This head comprises a center sleeve 43 encircling hub 31 and journaled in a main bearing M held by a housing 86, the bearing assembly being retained by rings .47 and 48. In order to permit axial as wellas rotational movement of the winding head, bearing housing 46 is supported on a slide rod d9 by arms 5! fastened to a block 52 secured tothe rod. Slidable support for the rod is provided by a collar 53 on plate I2 and a forward bracket 55 on bed plate 9. Centering of sleeve 33 on hub 31 is maintained by bearing rings '56. See Figure 6. i

A pair of large gears including a front gear 51 and a back-gear 58 are embodied in the Winding head mechanism. Front gear 51 runs at the speed of the head and is fixed to center sleeve 43. Back gear 58 is fixed to a second sleeve 59 which is loosely'journaled on center sleeve 43 by a bearing "ring 82. The'back gear is used for driving part of the'welding device as hereinafter described.

Both gears are rotated from main drive shaft 2'! by a gear 63 on the latter meshing with an idler '64 journaled on stub shaft 66 projecting from bracket G'lsecured to plate i2. See Figures and a stub shaft 69 projecting from bracket II also secured to plate i2. By this arrangement the two large gears on the winding head are rotated at different speeds.

Referring to Figures 5 and 6, the helical winding is applied by wire from a supply roll or reel 12 mounted on the winding head for movement in a path about the mandrel. The reel is journaled on a stub shaft 73 projecting from front gear 51 of the winding head, and is resiliently held by a spider 1e pressed by spring 16. Wire from this reel is directed onto the mandrel by an apertured guide tip l7 supported adjacent the mandrel by a bracket 18 mounted on the face of gear 51. The wire is thus applied as a helical wrapping over the longitudinal bars by reason of the combined rotational movement of the winding head and axial movement of the mandrel. Since one mandrel section follows immediately behind the other the grids are made continuously.

Pitch varying mechanism.Means are provided for varying the pitch of the winding at intervals along the axis to form close-turn end rings 3 and e and open-turn helices 6 on the grids. To accomplish this the winding head 42 is moved axially relative to the mandrel by a cam mecha nism. As shown in Figures 2, 3 and 6, a. cam 8| engages a foilower roller 82 on the end of slide rod 419. Contact between the follower and cam is maintained by a pair of springs 83 interposed between block 52 and plate l2. See Figure 10.

Cam 8! is carried by a shaft 84 journaled in housing 85 and connected to a cross shaft 81 by worm gearing 88. The cross shaft is in turn connected to main drive shaft 2! by a gear train 89.

Winding head 52 is thus caused to move forward with but slightly slower rate than the mandrel to form a pair of adjacent end rings 3 and 4, the cam being shaped to slow down a portion of this movement to provide some space between the two adjacent end rings so that the grids may be subsequently separated at this point. On the return stroke of the winding head the latter moves contra to the mandrel and forms the open turn helix 6.

Guide tip 38 for the longitudinal wires is maintained closely adjacent to-winding guide I1 by a yoke 8i secured to gear 51 and engaging a groove in tip 38 so that sleeve 38 slides back and forth with the winding head. Guide tip 38 is held against rotation by a fixed lug 92 engaging a slot 93 in the sleeve.

Welding mechanism-Means are provided for welding the wires together at their intersections immediately upon application of thehelical winding. As seen in Figures 5, 7 and 8, a welding electrode or roller 56 is carried on one end of an arm 8i which swings about a shaft 98 on a bearing 99, the roller assembly being counterbalanced .by a weight NH to compensate for centrifugal force. Roller 96 is positioned to ride on the wire being wound and is arranged to engage each in- :forvarying the spring pressureon the Welding r'oller.

being preferably of copper.

gear 58.

A third arm II2 pivoted between arm I08 and the face of gear 51 is arranged parallel to arm 9! to stabilize the linkage.

Means are further provided for positively driving weldin roller 95 at a peripheral speed sufficient to maintain a non-slipping rolling contact between the roller and wire. This eliminates disturbing the positions of the wires, which would occur if frictional contact with the wire were relied upon to turn the roller. Referring to Figures 2, 5 and 8, a chain H5 is connected between a sprocket ill on hub ltd and sprocket II 8 on shaft 98. The latter shaft is driven by back gear 58 through a planetary gear system comprising sun gear H9 on sleeve 59 meshed with a planet pinion i2i on the rear end of shaft 98. By this arrangement the welding roller is independently driven at a predetermined rate to maintain the desired rolling contact between it and the wire.

Means are also provided for supplying electrical current to the necessary parts for making the welds. In order to complete the electrical circuit we use mandrel I as one of the welding electrodes, both the mandrel and roller electrode 96 Contact with the mandrel is made by a pair of brushes I22 pivoted to housing 22 (Figure 2) and held together against the mandrel by a spring I23. As shown in Figure 3, a conductor I24 extends from one of these brushes to the welding transformer I26. Another oonductor IZI from the transformer leads to a terminal I28 on one of two conductive straps I29 supported by and insulated from block 52.

Straps I29 project upwardly to a slide contact device for feeding the current to the roller electrode. As shown in Figure 9 the contact device comprises a brush I3I connected to a strap I29 by a flexible conductor I 32. Brush i l slidably engages a conductive ring I33 secured to the back side of front gear 51 and insulated therefrom by an insulating ring I34. Brush pressure is maintained against ring I33 by a spring pressed arm I35 pivoted to the other upright strap I29. From collector ring I33 the current passes through stud III (Figure 7) which is also conductive and insulated from gear 51 by bushing I31. A flexible conductive strap I38 is connected between stud III and arm Hi6. To allow ample freedom of movement this stra is made in the form of a loop as seen in Figure 5. From arm I06 the current passes to roller electrode 96 by the contact surface between the arm and hub I4, the same being pressed together by a spring I39 interposed between the outer side of roller 96 and the end of axle I2.

Welding timer.Means are provided for timing the intermittently applied welding current so that the current flows only during the interval when roller electrode 96 is on an intersection or crossover of the wires. Any well known means such as Ignitrons may be employed in the primary circuit of the welding transformer for interrupting the current. We control the firing of the Ignitrons by a timer switch shown in Figures 2 and 5 comprising a pairof contacts I4I one of which is fixed and connected to a lead I42 and the other of which is movable and connected to a lead I43. The movable contact is mounted on the arm of a bell crank I44, the other arm of which rides on a cam having a fiat I 46. This cam is rotated by a pinion I41 meshed with back Contacts I 4! are normally held open by the bell crank arm riding on the cylindrical surface of the cam, but are closed once during each revolution when the crank arm rides on fiat I46. Since pinion I41 runs in timed relation with the winding head, the opening and closing of the switch will function as means for timing the welding operation. Complete connections from leads I42 and I43 to a control circuit for the transformer are not shown as this will be clear to thos skilled in the art. The timer device may be advanced and retarded by moving handle M8 to turn the entire switch about the axis of pinion I41, thus changing the instant at which the switch closes relative to the rotation of the pinion.

OpeTation.Befo-re starting the machine a mandrel is inserted through the windinghead and the longitudinal wires 2 are threaded through their respective slots 39 in guide tip 38. The ends of these wires are secured or clamped to the end of the first mandrel by any suitable means so that when the machine is started the wires will be peeled from reels 3| and laid along the mandrel by axial movement of the latter. The wire from reel 12 is then threaded through its guide l? and suitably secured about the mandrel so that when head 42 starts turning the wire will be wound.

The driving motor of shaft 2? is then started the power for the welding circuit turned on. This starts the mandrel feeding through the machine by the driving action of rollers I8. Simultaneous rotation of winding head 42 applies the helical wrapping, each intersection being welded by the synchronized welding mechanism. New mandrel sections are fed, one bethe other, to drive rolls I! so that grid fabrication proceeds continuously. As soon as a mandrel section advances a distance along the front guide trough I5 the mandrel is disconnected from the trailing one by cutting the wires at the junction between the mandrels. This is done while the mandrels are in motion and without stopping the machine.

The removed mandrel has a chain of say twenty-five or more grids on it. If the mandrel is sufficiently hard the individual grids may be cut apart directly on it by rolling under the knife 8 shown in Fi ure 1. Since the mandrel is used over and over it may be damaged by the knife. so we prefer to strip the chain of grids from the mandrel and slip them on a core of harder material for the cutting operation. The connected grids are easily stripped by applying tension at one end. If necessary. the grids may be first loosened by rolling the mandrel between two surfaces. After being separated the free ends of the wires are preferably trimmed up close to the end rings to produce the final grid as shown at the right in Figure 1.

We claim:

1. Ap aratus for making grids, comprising a mandrel. means for axially moving the mandrel, mechanism o erable u on movement of the mandrel for laying a plurality of wires l0hgitudinally along the mandrel. means for winding another wire helically about the mandrel, and

.means for uniting the wires at intersections thereof.

2. Apparatus for making grids, comprising a mandrel, means for axially moving the mandrel, mechanism operable uponmovement of the mandrel for laying a plurality of wires longitudinally along the mandrel. means for winding another wire helically about the mandrel, means for moving the last mentioned means relative to the mandrel for varying the pitch OfthBfWiIldilIlE,

and means for uniting the wires at intersections thereof.

3. Apparatus for making grids, comprising a mandrel, means for axially moving the mandrel, means for laying a plurality of wires longitudinally. along the mandrel, said means including a series of supply rolls of said wires circumferentially. spaced around the mandrel, means for winding another wire helically about the mandrel, said last mentioned means including a supply roll of said other wire movable in a path around the mandrel, and means for uniting the wires at intersections thereof.

4. Apparatus for making grids, comprising a mandrel, means for axially moving the mandrel, means for laying a plurality of wires longitudinally along the mandrel, said means including a series of supply rolls of said wires circumferentially spaced around the mandrel, means for winding another wire helically about the mandrel, said last mentioned mean including a supply roll of said other wire movable in a path around the mandrel, means for moving the last mentioned supply roll axially relative to the mandrel for varying the pitch of the winding, and means for uniting the wires at intersections thereof.

5. Apparatus for making grids, comprising a rotatable winding head, a mandrel, means for axially moving the mandrel through said head, mechanism operable upon movement of the mandrel for laying a plurality of wires longitudinally along the mandrel, guide means on the head for directing another wire in a helical winding about the mandrel, and means for uniting the wires at intersections thereof.

6. Apparatus for making grids, comprising a rotatable winding head, a mandrel, means for axially moving the mandrel through said head, guide means for directing a plurality of wires longitudinally along the mandrel, guide means on the head for directing another wire in a helical winding about the mandrel, mechanism synchronized with rotation of said head for moving the head axially relative to the mandrel to vary the pitch of the winding, and means for 8. Apparatus for making grids, comprising a rotatable winding head, a mandrel, means for axially moving the mandrel through said head, guide means for directing a plurality of wires longitudinally along the mandrel, guide means on the head for directing another wire ina helical winding about the mandrel, and means including an electrode carried by said head for welding the wires at intersections thereof, said electrode being arranged to contact an intersection at the point where the wire being wound approaches the mandrel.

9. Apparatus for making grids, comprising a rotatable winding'head, a mandrel, means for axially moving the mandrel through said head,

guide means for directing a plurality of'wires longitudinally along the mandrel, guide means on the head for directing'another wire ina helical winding about the-mandrel, means ineluding a roller electrode carried by said head for welding the wires at intersections thereof, and a planetary gear system for driving said electrode.

10. Apparatus for making grids, comprising a frame, a mandrel, means on the frame for axially moving the mandrel, a series of supply rolls of wires arranged on the frame circumferentially spaced around the mandrel, guide means on the frame for directing said wires longitudinally along the mandrel, a rotatable winding head on the frame encircling the mandrel, a supply roll of another wire on said head, guide means on the head for directing said other wire in a helical winding about the mandrel, and means for uniting the wires at intersections thereof.

11. Apparatus for making grids, comprising a metallic mandrel, means for axially moving the mandrel, mechanism operable upon movement of the mandrel for laying a plurality of wires longitudinally along the mandrel, means for winding another wire helically about the mandrel, an electrode engageable with an intersection of the wires, and means for passing an electric current through the electrode and mandrel and the interposed wires to weld the latter together.

12. Apparatus for making grids, comprising a metallic mandrel, means for axially moving the mandrel, means for laying a plurality of wires longitudinally along the mandrel, means for winding another wire helically about the mandrel, a roller electrode riding on the last mentioned wire and engageable with successive intersections of the wires, and means for passing an electric current through the electrode and mandrel and the interposed wires to weld the latter together.

13. Apparatus for making grids, comprising a metallic mandrel, means for axially moving the mandrel, means for laying a plurality of wires longitudinally along the mandrel, means for winding another wire helically about the mandrel, a roller electrode riding on the last mentioned wire and engageable with successive intersections of the wires, means for driving the roller electrode, and means for passing an electric current through the electrode and mandrel and the interposed wires to weld the latter together.

14. Apparatus for making grids, comprising a frame, a bearing on the frame, a mandrel, means for axially moving the mandrel through said bearing, guide means on the frame for directing a plurality of wires longitudinally along the mandrel, a winding head journaled in said bearing, and means on the head for directing another wire in a helical winding about the mandrel.

15. Apparatus for making grids, comprising a frame, a bearing movably mounted on the frame, a mandrel, means for axially moving the mandrel through said bearing, guide means on the frame for directing a plurality of wires longitudinally along the mandrel, a winding head journaled in said bearing, means on the head for directing another wire in a helical winding about the mandrel, and means for axially moving the bearing for varying the pitch of the winding.

16. Apparatus for making grids, comprising a plurality of mandrels'disposed end-to-end, means for axially moving the mandrels, mechanism op-' Lof' grids, means for winding another wire heli- 10 cally about the mandrels, and means for uniting mandrel, and means for uniting the wires at the wires at intersections thereof. intersections thereof.

1'7. Apparatus for making grids, comprising a DONALD F. DRIESCHMAN. mandrel, means for axially moving the mandrel GORDON SHEPHERD. without rotation, means for laying a plurality of 5 MIENDEL RABINAWITZ. wires longitudinally along the mandrel, means ALMER M. NEWHALL, JR.

for winding another wire helically about the HAROLD E. SORG, 

